Lobelia deckenii

{{Short description|Species of plant in the family Campanulaceae}}

{{Speciesbox

| image = Lobelia gregoriana.jpg

| genus = Lobelia

| species = deckenii

| authority = (Asch.) Hemsl.{{cite web|url= https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:143159-1|title= Lobelia deckenii (Asch.) Hemsl.|author=|date=n.d.|website=Plants of the World Online|publisher=The Trustees of the Royal Botanic Gardens, Kew|access-date= September 27, 2020}}[http://www.ipni.org/ipni/idPlantNameSearch.do?id=143159-1 International Plant Names Index]

| synonyms = Dortmanna deckenii (Asch.) Kuntze

Tupa deckenii Asch.

Tupa kerstenii Vatke

| synonyms_ref =

}}

Lobelia deckenii is a species of flowering plant in the family Campanulaceae.{{cite web|url= http://www.worldfloraonline.org/taxon/wfo-0000814507|title= Lobelia deckenii (Asch.) Hemsl.|author=|date=n.d.|website=World Flora Online|publisher=The World Flora Online Consortium|access-date= September 27, 2020}} It is a giant lobelia endemic to the mountains of Tanzania. It is listed as a threatened plant of the forests of Cherangani hills, Kenya.{{cite journal |last1=Mbuni |first1=Yuvenalis Morara |last2=Zhou |first2=Yadong |last3=Wang |first3=Shengwei |last4=Ngumbau |first4=Veronicah Mutele |last5=Musili |first5=Paul Mutuku |last6=Mutie |first6=Fredrick Munyao |last7=Njoroge |first7=Brian |last8=Kirika |first8=Paul Muigai |last9=Mwachala |first9=Geoffrey |last10=Vivian |first10=Kathambi |last11=Rono |first11=Peninah Cheptoo |last12=Hu |first12=Guangwan |last13=Wang |first13=Qingfeng |title=An annotated checklist of vascular plants of Cherangani hills, Western Kenya |journal=PhytoKeys |date=18 April 2019 |issue=120 |pages=1–90|doi=10.3897/phytokeys.120.30274 |doi-access=free |pmid=31065231 |pmc=6483958 |bibcode=2019PhytK.120....1M }}

It grows in moist areas, such as valley bottoms and moorland, in contrast to Lobelia telekii which grows in a similar but drier habitat. These two species produce occasional hybrids. Lobelia deckenii plants usually produce multiple rosettes. Each rosette grows for several decades, produces a single large inflorescence and hundreds of thousands of seeds, then dies. This is called monocarpy. Because individual plants have multiple rosettes, they survive to reproduce repeatedly, and plants with more rosettes flower more frequently. Each rosette of yucca-like leaves with its inflorescence can reach a maximum height of {{cvt|3.7|m}}. The flowers are pollinated by sunbirds (Nectariniidae).{{ cite book | last1=Everard |first1= Barbara | last2= Morley | first2= Brian D. | date=1970 | title= Wild Flowers of the World | location= New York | publisher= G.P. Putnam's Sons | page= Plate 56 }} It is iteroparous.{{cite journal | last = Young

| first = Truman P. | title = The comparative demography of semelparous Lobelia telekii and iteroparous Lobelia keniensis on Mount Kenya | journal = Journal of Ecology | volume = 72 | issue = 2 | pages = 637–650 | year = 1984 | doi =10.2307/2260073 | jstor =2260073| bibcode = 1984JEcol..72..637Y }}

Lobelia deckenii plants usually form between one and eighteen rosettes which are connected underground. The individual rosettes grow slowly in the alpine environment, and may take decades to reach reproductive size. The rosette that produces an inflorescence dies after flowering, but the remaining connected rosettes live on.

Lobelia deckenii is the only alpine species of lobelia that is native to Kilimanjaro,Young, T.P. 1991. La flora, fauna y ecología del Monte Kenia y el Kilimanjaro. Pp. 37-49 En: Guía para el Monte Kenia y el Kilimanjaro (Iain Allan, ed.) Mountain Club of Kenya {{ISBN|978-9966-9856-0-6}} occurring between {{convert|3,800|and|4,300|m|ft|abbr=on}}.Kilimanjaro. Oh rei da áfrica. Revista Planeta, dezembro de 2005.

Lobelia deckenii subsp. keniensis is the variety of Lobelia deckenii that occurs on Mount Kenya, between {{convert|3,300|and|4,600|m|ft|abbr=on}}. It is eaten less by rock hyrax than Lobelia telekii, which occurs more often in hyrax habitat. The lobelia species on Mount Kenya are both pollinated by birds,{{cite journal | last = Young | first = Truman P. | title = Bird visitation, seed set, and germination rates in two species of Lobelia on Mount Kenya | journal = Ecology | volume = 68 | issue = 6| pages = 1983–1986 | year = 1982 | doi =10.2307/1940139 | jstor = 1940139 | bibcode = 1982Ecol...63.1983Y }}{{cite journal | last = Burd | first = Martin

| title = Pollinator behavioural responses to reward size in Lobelia deckenii: no escape from pollen limitation of seed set | journal = Journal of Ecology | volume = 83 | issue = 5| pages = 865–872

| year = 1995 | doi =10.2307/2261423 | jstor = 2261423

| bibcode = 1995JEcol..83..865B

}} especially the scarlet-tufted sunbird and the alpine chat.{{cite journal

| last = Smith | first = Alan P. |author2=Truman P. Young | title = Tropical Alpine Plant Ecology | journal = Annual Review of Ecology and Systematics | volume = 18 | pages = 137–158

| year = 1987 | issue = 1 | doi = 10.1146/annurev.es.18.110187.001033 | bibcode = 1987AnRES..18..137S }}

This species of giant lobelia is known for the reservoirs of water held in its rosettes, which freeze at night and protect the apical meristem which is contained in a dense central leaf bud. When this reservoir is drained, the temperature of the inner meristem drops below freezing, which does not occur when the fluid is left intact.{{cite journal | last = Young | first = Truman P. |author2=Susan Van Orden Robe | title = Micro-environmental role of a secreted aqueous solution in afro-alpine Lobelia keniensis | journal = Biotropica | volume = 18 | issue = 3 | pages = 267–269 | year = 1986 | doi = 10.2307/2388496 | jstor = 2388496 }} The crescent-shaped ice cubes formed in these rosettes gave rise to the nickname, "gin and tonic lobelia".{{cn|date=June 2025}}